My lines not getting darker?

JJ • River Henry 5/6/18 and number 2 due in September/October!

I know hcg doubles every 48 hours but I've been testing every 24 and every morning I've had a dark increase of lines. This morning, not so much.

I did drink a lot of herbal tea yesterday but I'm freaking out. I also realize the top test is 24 hours old and it darkens as the day goes on but every day has been a big increase.

Should I worry?

Top yesterday, bottom today:

Past day progress (24 hours)